A fire in the interior space of an air cargo container and/or the air cargo container itself causes material damages due to the fact that the content of the air cargo container might become useless. Furthermore, there is the danger that a fire of or in an air cargo container might have negative effects on the neighborhood of the air cargo container. The fire might expand or build a source of heat causing additional damages. Finally, the fire might cause damages due to smoke or might threaten the health of persons in the neighborhood of the air cargo container.
As an order of the Spanish air force the company VRR Air Cargo Equipment developed an air cargo container with an interior space limited by a rigid metallic housing. Fire extinguishers were fixed at the housing for injecting an extinguishing agent into the container in case of a fire (see http://www.vrr-aviation.com/products/military/aay-container-fire-containment-container-(fcc)).
German patent application DE-OS 1 786 205 discloses an air cargo container built by a plane bottom plate and a flexible wall which is pumped up similar to an air cushion or air bed. The wall builds a thermic isolation. In an unloaded operation configuration of the air cargo container the wall is folded for occupying a reduced space only slightly exceeding the volume of the bottom plate. In case that the air cargo container is to be loaded, the walls are built up by inflating the walls similar to air beds with a pressurized gas. The container might comprise an opening for loading and unloading. The opening is closed by a closing element with a zip fastening. An upper or sealing curvature of the wall might be adapted to the curvature of the storage space of the airplane. The bottom plate might comprise mounting devices for anchoring the bottom plate with the storage space of the airplane. Further supporting devices (as a support in the shape of a metal or plastic tube inserted between the bottom plate and the sealing wall, in particular located close to the opening for loading and unloading) might also be provided. The document suggests using a wall being impermeable for gas, e.g. a wall made of a rubber fabric. The wall might have tube-like sections that can be filled with a gas. The document also suggests filling these tubes with nitrogen for extinguishing a fire.
German patent application DE 26 56 639 A1 discloses a foldable container for a liquid or solid cargo. The container is built with a tube-like or bag-like wall spanned by a flexible, foldable or telescopable support structure between a bottom plate and a cover plate. The document suggests choosing a support structure having a high resistance against fire and high temperatures or having self-extinguishing properties in case of a fire.
German patent DE 103 18 975 B3 (see U.S. Pat. No. 7,506,478 B2) discloses a method for extinguishing a fire in a closed space of an airplane, in particular in an overhead bin in a passenger compartment or in a container in the cargo compartment of an airplane. Generally, a space protected against the build-up of a fire should be sealed so that the amount of oxygen for the fire is limited. Undesired leakages of these spaces lead to the disadvantage that the fire is supplied with additional oxygen. On the other hand, smoke might leak into the neighbouring spaces. The patent suggests locating a material close to an expected leaking area which foams and changes its volume when heated. In case of a fire building up the material foams and automatically seals the undesired leakage. Accordingly, the supply of oxygen via the leakage is reduced or terminated.
German patent application DE 103 58 978 A1 discloses a fire protection element having a compact configuration for storage. In case of a fire the fire protection element is thrown over the fire where the fire protection element automatically unfolds from the compact configuration to an extended configuration for building a fire blanket. Such an automatically expanding fire blanket is proposed for use in case of a fire in a domestic home, in buildings, vehicles, in the forest, in chemistry, for burning oil, burning electronic components and for smoldering fires. The patent application suggests equipping the fire protection element with an expander. The expansion of the expander is triggered by a trigger. The trigger might be activated manually when throwing the fire protection element, with the impact of the fire protection element with the burning material, by radio frequency or wirelessly or by a sensor sensing a temperature, smoke or radiation. The energy of the expander might be stored as an elastic pretension, a pressure of a pyrotechnic gas generator, a gas cartridge, the energy of the throw or an archimetric lifting force. For applications with fire classes A, B and C the document suggests to wet the fire blanket already in the storage configuration, equip the fire blanket with internal water bags or wet the fire blanket immediately before its use. It is also possible to manufacture the fire blanket from a non-conducting electric material as ceramics or plastic. Furthermore it is possible to use a surface coating for influencing the radiation. Additional to the automatically triggered expansion by the cooperation of the trigger with the expander the deformable fire blanket might automatically adapt to the contour of the burning materials due to its weight. It is possible that the expander due to the high temperature or also automatically loses its stiffness after the expansion. However, it is also possible that the expander is stiffened after being unfolded such that the fire blanket might build a self-supporting wall for blocking or redirecting the flame front, limiting a fire or enclosing an object to be protected. In order to remove oxygen from a fire in closed spaces, the patent application also suggests using an expanding fire protection element with an interior space. With the expansion the volume of the interior space increases. Air or oxygen is drawn into the interior space for reducing the free air or oxygen available for the fire.